SuperSearch v0.1.13

Extends the base theme to the main palette window (it only ever reached the
Settings window before), surfaces failed open/launch actions instead of
silently closing, and removes a rendering artifact around the palette.

Fixed

• Theme choice didn't apply to the palette. Each Tauri window is its own
  webview with an independent document; picking Light in Settings only
  ever set data-theme on the Settings window's own document; the main
  palette never called applyTheme() at all, so it always rendered the dark
  default no matter what was chosen — looking like the setting kept
  resetting on every summon. The palette now applies the persisted theme on
  boot and live on every settings-changed broadcast, the same way it
  already did for accent color. Converted the palette's own hardcoded
  white/* and hsla(32,14%,6%,…) tokens (App.tsx, CommandItem.tsx,
  DetailPane.tsx, categories.ts) to the ink/canvas semantic colors
  introduced in 0.1.12 so Light actually repaints it, not just Settings.
• Failed file/app opens closed the palette with zero feedback.
  execute_action always reported acknowledged: true even when the
  underlying open/xdg-open call failed (bad or stale path, no default
  handler, a permission gate, …), and the frontend never inspected the
  response before closing — a failed open and a successful one looked
  identical to the user. Added an explicit success field to
  ExecuteActionResponse; the palette now only closes on success and
  otherwise keeps the panel open with an inline error banner naming the
  actual OS-level failure.
• Translucent rectangle around the palette. The panel's ambient
  box-shadow (blur-90px/spread--20px) reached far past the 12px padding
  around it, but the window itself is transparent with no native shadow —
  so the shadow's soft gradient got hard-clipped at the window's true
  rectangular bounds instead of fading out, showing as a faint rectangular
  edge floating around the rounded card. Shrunk the shadow to fit inside
  the existing padding so it now fades to nothing before it ever reaches
  the window edge.